Mylotarg Withdrawal Raises Questions

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Gail Dutton

Pfizer agreed today to withdraw its therapy for acute myeloid leukemia, Mylotarg (gemtuzumab ozogamicin), from the U.S. market, effective October 15. The reason? It didn’t work, and people died.

So far, the story makes sense. Developed by Wyeth, the drug was fast-tracked to treat patients ages 60 and older with recurrent AML who were not candidates for other chemotherapy. It was approved by the FDA in May 2000 based upon a surrogate endpoint, because it treated a serious disease that had no other viable therapy.

Four years later, a confirmatory trial was begun to confirm the results of the 142 patients who participated in the three previous clinical trials. Given the circumstances, the failure and subsequent withdrawal makes sense.

What doesn’t make sense is what comes next. Wyeth stopped the 2004 trial early because patients experienced no clinical benefit and died in greater numbers than those receiving chemotherapy alone.

So, why did it take so long to withdraw the drug? Why is Mylotarg being withdrawn only for the U.S. market? Why does the withdrawal become effective October 15, three and one half months from now?

Why are patients who are on Mylotarg allowed to continue a therapy that, according to the FDA, “demonstrates no clinical benefit?”